18139540 has 24 divisors (see below), whose sum is σ = 38328192. Its totient is φ = 7211040.

The previous prime is 18139531. The next prime is 18139543. The reversal of 18139540 is 4593181.

It is a super-2 number, since 2×18139540² = 658085822823200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18139543) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 625 + ... + 6055.

It is an arithmetic number, because the mean of its divisors is an integer number (1597008).

Almost surely, 2^18139540 is an apocalyptic number.

18139540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18139540 is an abundant number, since it is smaller than the sum of its proper divisors (20188652).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18139540 is a wasteful number, since it uses less digits than its factorization.

18139540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5607 (or 5605 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 18139540 is about 4259.0538855478. The cubic root of 18139540 is about 262.7496159241.

The spelling of 18139540 in words is "eighteen million, one hundred thirty-nine thousand, five hundred forty".